More than 2, 000 workers at five of Amazon's nine distribution centers in the country went on strike Monday, reported Reuters. Workers at a sixth facility are expected to join the strike on Tuesday, said Verdi. The strike coincides with the busy holiday shopping season, and Verdi said delays to deliveries could not be ruled out as a result of the strikes, according to Reuters.

Amazon did not immediately respond to a request for comment.

Amazon and Verdi have been battling over worker wages for the past year, with no end in sight. Verdi argues that Amazon's workers across Germany should be considered mail order and retail employees -- putting them in an industry that has higher average wages -- and not logistics workers. Amazon has said the workers are logistics employees and they make wages that exceed industry standards in Germany.

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Verdi organizing the strike at this time of the year is no surprise. While the labor union has staged protests over the past several months, it tends to focus the walk-offs at times Amazon has the most orders to fulfill. With the holiday shopping season now in full swing, it appears Verdi is trying to make a statement.

The trouble is that Verdi has been hard-pressed to find enough people to make a dent in Amazon's order fulfillment. Just last week, Verdi staged a strike at Amazon's Bad Hersfeld facility, but could only get 450 people to walk off the job. Amazon has 10,000 regular workers at its facilities and adds another 10,000 during the busy holiday shopping period.

Verdi said it will continue its protests through Wednesday, according to Reuters.